How fashions change. For so long one of the most popular operas in the repertoire, with its Miserere chorus widely considered the world's favourite opera melody, Il trovatore can now be described in a programme note as "almost a neglected work". Happily, it is not neglected by Welsh National Opera which this week began its autumn visit to Oxford's New Theatre with a revival of the production (which originated with Scottish Opera) first seen here four years ago.

A possible reason for the opera's decline in popularity during recent years is a growing realisation of the absurdity of its plot. Whereas opera-goers of the past would have simply sat back and enjoyed the feast of glorious tunes Verdi provides, audiences of today, following every twist of the action in surtitles, must confront the fatuous features of the story. The silliest of all (for all that it is said in another programme note to be wholly credible) is the deed on which the plot hinges - a woman accidentally throwing her own baby, rather than someone else's, on to a funeral pyre. Moreover, this startling event is not even depicted on the stage but included among the narrated 'back story' that occupies so much of the first two acts.

But this is in some ways an unfair criticism, for Il trovatore long predates attempts at verismo in opera. It is, in fact, a glorious example of all that is best in the bel canto tradition. The florid ornamentations and trills demanded of the singers are nowhere better supplied in this production than by soprano Katia Pellegrino (pictured) in the role of Leonora. Her great Act IV aria D'amor sull' ali rosee was for me the musical high spot of the evening - and, to judge from the applause, others felt the same.

At this point, Leonora is on a mission to rescue her lover Manrico (Luis Chapa) from the clutches of Count di Luna (Dario Solari), his unsuccessful rival for her affections. The young gypsy (as he is considered to be) had been trapped while trying to save his 'mother' Azucena (Anne-Marie Owens) from a date at the stake, she having been identified by a courtier as the child-thrower (aforementioned) at the immolation of her own mother after accusations of witchcraft. In fact, as we learn in the last moments of the opera, Manrico is not Azucena's child - that baby perished in the flames - but actually the count's presumed-to-be-dead brother.

But while credibility is stretched to breaking point, there can be no denying the fervent efforts the composer made to supply music to match character and action. Conductor Michal Klauza guides the considerable forces of WNO's singers and orchestra in a truly sensational exploration of the beauties of the score. The sombre tone of drama is well-matched in the spartan designs of Tim Hatley - interlocking sections of curved grey wall - and Davy Cunnningham's lighting. So much is blackness, redeemed - though this is hardly the word - by flashes of red fire.

There is a further performance of Il trovatore tonight, with Rossini's La Cenerentola following tomorrow.